Migration Matters says arrivals will probably peak at about 20,000 rather than 300,000 as claimed

Romanians and Bulgarians will gain full rights to work in the UK from 2014. Photograph: Rex Features

The number of Romanians and Bulgarians to arrive in the UK next year may be as few as 20,000, according to a cross-party lobby group, Migration Matters Trust.

Atul Hatwal, director of Migration Matters, said the estimate – far lower than competing claims by groups such as MigrationWatch – was based on analysis of historical EU migration patterns, macro-economic factors such as the impact of the recession on the UK, and limited job opportunities in areas such as manual labour.

Ministers have so far refused to put a figure on the likely influx, although last week the Office for National Statistics estimated that 37,000 extra Romanian and Bulgarian workers have arrived since June last year, prompting speculation that citizens of the two countries were already preparing for life in Britain even before border controls are lifted on New Year’s Day.